Recent legislative and regulatory changes have been made to spur a more open service provider environment in the telecommunications industry. One aspect of this policy is embodied in a requirement that an incumbent local exchange carrier (ILEC) unbundle certain network elements and services and offer use of those elements and services to other carriers for resale to end users. The ILEC, for example, must make available for sale to another carrier an unbundled port on an end office switch. The other carrier can then become a competing local exchange carrier (CLEC) by reselling services of the switch to end users having local loops that connect to the end office switch. Those statutory and regulatory changes also require that customized routing be available for both unbundled switching and for resale. Customized routing is the term used in the regulations for routing calls made in the ILEC switch to locations other than normal routing locations.
Another aspect of this policy pertains to CLECs that are facility based, e.g., those competing carriers that have their own independent switching facilities. These facilities must be integrated into the public switched telephone network (PSTN) in a seamless manner from the user's perspective. The concept of user telephone number portability is basic to this end. In general, number portability refers to the ability of end users to retain their geographic or non-geographic telephone number when they change their service provider, their location, or their service. A wide application of number portability, for example, would permit a user to keep the same telephone number at the same or different location, while terminating service from one provider in favor of a new service provider, and moving from plain old telephone service (POTS) to integrated digital services network (ISDN).
The Federal Communications Commission has proposed standards for local number portability (LNP) that relates to the ability of a telephone service subscriber to select or change the selection of a carrier for providing that customer's local telephone service, while still maintaining the subscriber's telephone number at the same customer premises. The physical aspects of maintaining the same telephone number for a customer while changing service from an ILEC to a CLEC using an unbundled port on the same switch are relatively straightforward. Provision of local number portability for a change of local service from an ILEC to a provider having its own switching facility with its own subscriber loop or unbundled loop between its switch and the customer's premises, is more problematical. The network must be capable of routing calls dialed to the same subscriber's number through the changed facilities. While an actual change of connections from the old ILEC plant to the new CLEC plant at the premises by a technician will permit customer off-hook to draw dial tone for calling out via the CLEC line, the ability to receive incoming calls is not so easily effected. Incoming call routing is dependent upon the association of the new customer line with the appropriate routing information in the PSTN network.
Until the subscriber's telephone number is identified in the system with the new CLEC destination line or the CLEC switch to which it is coupled, the subscriber cannot receive incoming calls to that line. If physical reconnection has been established, no incoming calls will be received via the old ILEC subscriber line. Service disruption, besides being annoying and unacceptable to the subscriber, is a serious disadvantage in that the ability to provide adequate 911 emergency service is compromised. The 911 service center, which has access to the originating numbers of callers, will not be able to terminate calls to users who are in the process of changing service providers. To avoid unacceptable delay in service, the physical line reconnection must be closely coordinated with a change in system database information. Such a requirement places a burden on technician resources and incurs increased expense in providing appropriate use of such resources.
Several arrangements have been proposed for allowing a customer access to one of several carriers to which the customer may concurrently subscribe. For example, U.S. Pat. No. 5,341,415, issued to Baran, is directed to a method and apparatus for sharing common in-house wiring to permit multiple telephone carriers to serve the same customer. The primary, or default, carrier is envisioned as the local telephone company, while a secondary carrier may comprise a cable TV system or the like. The user selectively may dial out through either carrier. The subscriber line is normally connected to the primary carrier, normally disconnected from the secondary carrier. A predesignated DTMF code may be entered, prior to dialing out, to select the secondary carrier, whereby the reverse connections and disconnections are effected. Incoming calls via the secondary carrier can be completed only if no call via the primary carrier is in progress, with appropriate connections made. Routing of incoming calls is made pursuant the dialed number for the user that corresponds to the respective carrier. U.S. Pat. No. 5,408,525, issued to Eldering, is directed to a `diverter` at the user site for selectively interfacing a customer's standard telephone set on an in-house line with a first external telephone line and a second external telephone line from competing carriers. If the user wants to use the secondary line, the user first dials an access code. A set monitor in the diverter detects the code and triggers a switch to connect the in-home line to the secondary line. Ring detectors are included in the diverter for switching the in-home line to either line in response to an incoming call. Neither patent provides for local number portability wherein the subscriber retains the same telephone number for a new carrier service provider that was used for the earlier, terminated, carrier service provider. The public switched telephone network will route calls through to the carrier associated with the dialed number. There is no change in routing for that number. Both patents are directed to customer controlled, rather than provider controlled, cutover mechanisms.